Device for Fastening A Turbojet Engine to an Aircraft Fixing Strut

ABSTRACT

A front attachment device for fastening a turbojet engine to an aircraft fixing strut. The attachment device is adapted to absorb the turbojet engine thrust loads, and includes a top bracket, and a lower bracket. A thrust load absorption vector results from a first convergence point of primary vectors passing through primary fixing points that couple the top bracket to the lower bracket and a second convergence point of secondary vectors passing through secondary fixing points that couple the lower bracket to the turbojet engine. The thrust load absorption vector transmits the turbojet engine thrust loads to the fixing strut, and extends along a longitudinal axis of the turbojet engine.

RELATED APPLICATIONS

This application is a national stage entry under 35 U.S.C. § 371 of PCTApplication No. PCT/FR2006/051093, filed Oct. 24, 2006, which claimspriority from French Application Number 0553304, filed Oct. 31, 2005,the disclosures of which are hereby incorporated by reference herein intheir entirety.

FIELD OF THE INVENTION

The invention relates to an attachment device for connecting a turbojetengine to an aircraft fixing strut. More particularly, the inventionrelates to a front attachment device adapted to absorb thrust loads towhich an aircraft turbojet engine is submitted.

BACKGROUND OF THE INVENTION

A turbojet engine can be mounted at various locations of an aircraft,through a fixing strut belonging to said aircraft's structure. Forinstance, the turbojet engine can be suspended, through said fixingstrut, to the aircraft wing intrados, or attached laterally to thefuselage, or else mounted, at the rear of the aircraft, on the rearvertical empennage. The function of fastening structures connecting thefixing strut to the turbojet engine is to ensure the transmission ofmechanical force between the turbojet engine and the aircraft structure.

The force transmitted to the aircraft structure through the fasteningstructures are mainly thrust loads from the turbojet engine, extendingparallel to the turbojet engine axis, lateral forces mainly due to windgusts to which the turbojet engine and the aircraft are generallysubmitted, and vertical forces from said turbojet engine mass. Thefastening structures should also absorb turbojet engine distortions,i.e., from dimensional variations due to thermal dilations orcontractions during various aircraft flight phases.

Generally, fastening structure for fastening the turbojet engine to theaircraft fixing strut includes a front attachment device and a rearattachment device.

Fastening structures commonly used include the turbojet engine centralcowl attached to the fixing strut using a front attachment device and arear attachment device. In that case, the front attachment deviceabsorbs the turbojet engine thrust loads as well as the lateral andvertical forces. The rear attachment device absorbs lateral and verticalforces.

Other fastening structures include a front attachment device, arrangedbetween the fixing strut and the fan cowl, which absorbs lateral andvertical forces, and a rear attachment device, arranged between thefixing strut and the central cowl, which absorbs thrust loads, lateralforces and vertical forces. Thrust loads are then absorbed through twolong rods, connecting the rear attachment device to a front part of thecentral cowl.

As a result of the turbojet engine thrust loads, and more specificallyfrom said thrust load absorption by the attachment device and the fixingstrut, the turbojet engine is submitted to significant bending, whichtends to decrease the turbojet engine life span.

The present invention provides a device for fastening a turbojet engineto a fixing strut adapted to absorb the turbojet engine thrust loads andto transmit them to the fixing strut, without subjecting the turbojetengine to significant bending forces.

In that regards, the invention includes a front attachment mechanism,connecting the fixing strut to the turbojet engine fan cowl, forming athrust load absorption vector resulting from different attachment pointsbetween aforesaid front attachment mechanism and the turbojet engine,which is directly coincident with the turbojet engine axis. The frontattachment mechanism according to the invention includes an intermediatepart, positioned under a main part of the turbojet engine frontattachment mechanism. The intermediate part is linked to the main partby a first attachment system, which convergence point is located on theturbojet engine axis. The intermediate part is also connected to theturbojet engine through a second attachment system, which convergencepoint is also located on the engine axis, but upstream from the firstattachment system convergence point. The front attachment mechanismaccording to the invention behaves as if the engine thrust wastransiting between both attachment system convergence points of saidfront attachment mechanism, i.e. following the turbojet engine axis, andtherefore without generating the slightest bending of said turbojetengine, the torque being naturally absorbed completely by the fixingstrut.

The second attachment system, connecting the intermediate part to theturbojet engine, includes, for example, a rod system in the front andanti-torque controls in the rear. Front and rear as used herein aredesignated in relation to the moving direction of an aircraft havingsuch turbojet engine. The intermediate part according to the invention,since the anti-torque controls and rod systems are connecting it, on theone hand, to the turbojet engine and, on the other hand, to the mainpart of the front attachment mechanism, has particular kinematicsenabling a thrust load transfer along the axis of the turbojet engine.The geometry of the front attachment mechanism according to theinvention is designed so that the resulting force from the variousfixing points is coincident with the turbojet engine axis, so that saidturbojet engine is not submitted to any bending force.

Therefore, the invention provides a front attachment device forfastening a turbojet engine to an aircraft fixing strut adapted toabsorb said turbojet engine thrust loads, wherein the front attachmentdevice includes a top bracket, a lower bracket, primary fixing pointsconnecting said top bracket to lower bracket, and secondary fixingpoints connecting said lower bracket to said turbojet engine, theabsorbing thrust loads vector which results, on the one hand, from theconvergence point of the primary vectors passing through the primaryfixing points, and, on the other hand, from the convergence point of thesecondary vectors passing through the secondary fixing points, and whichtransmits the turbojet engine thrust loads to the fixing strut, extendsalong the axis of the turbojet engine.

Fastening point used herein is defined as any punctual attachmentmechanism, enabling connection of one element to another through aspecific point.

In particular examples of embodiment of the front attachment deviceaccording to the invention, said device may include all or parts of thefollowing additional characteristics:

-   -   the primary vector convergence point is located on the turbojet        engine axis;    -   the secondary vector convergence point is located on the        turbojet engine axis;    -   the primary vector convergence point is located downstream from        the secondary vector convergence point;    -   the front attachment device includes primary attachments with at        least one front primary rod and at least one rear primary rod,        in order to connect the top bracket and the lower bracket        through two primary fixing points;    -   the front attachment device includes secondary attachments with        at least one secondary front rod, and at least two secondary        rear rods, in order to connect the lower bracket and the        turbojet engine fan cowl through three secondary fixing points;    -   both secondary rear rods are mounted on the lower bracket        through anti-torque controls; and/or    -   the top bracket is also connected to the turbojet engine fan        cowl.

The invention will be better understood by reading the followingdescription and examining the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view depicting a front attachment deviceaccording to an embodiment of the invention;

FIG. 2 is a schematic rear view depicting the attachment device of FIG.1 according to an embodiment of the invention; and

FIGS. 3A, 3B, and 3C are a schematic views depicting the connectionbetween an aircraft's fixing strut, attachment device according to anembodiment of the invention, and turbojet engine.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIGS. 1 and 2, a fixing strut 3 is coupled to a fan cowl 2 of aturbojet engine 1. Fixing strut 3 is connected to aforesaid fan cowl 2by a front attachment device 100 according to an embodiment of theinvention.

Front attachment device 100 includes a top bracket 101 and a lowerbracket 102 located below top bracket 101. Top bracket 101 is coupled,in a traditional way, on the one hand, to fixing strut 3 and, on theother hand, to a rear structure 4 of fan cowl 2. More precisely, topbracket 101 is mounted stationary onto fixing strut 3 located above saidtop bracket 101. The connection between top bracket 101 and a centralpart 6 of rear structure 4 of fan cowl 2 is secured by two rods 5 (onlyone rod is visible in FIG. 1). Rear part 4 of fan cowl 2 has asemicircular shape following an upper contour of the cylindrical part ofthe turbojet engine circular. Rear part 4 of fan cowl 2 has anappreciably inverted-U shape, the base of said U forming central part 6,and each branch 7 of the U fitting on a right or left side of thecylindrical part of turbojet engine 1.

According to an embodiment of the invention, top bracket 101 isconnected to lower bracket 102 by primary attachments 103, 108. Forexample, as represented in FIGS. 1 and 2, top bracket 101 is connectedto top bracket 102 by a primary rod system 103, 108. More particularly,two rear primary rods 103 connect a rear extremity 104 of top bracket101 to a rear extremity 105 of lower bracket 102. Front extremity 106 oftop bracket 101 is, itself, connected to front extremity 107 of lowerbracket 102 by two front primary rods 108 (only one front primary rod isvisible in FIGS. 1 and 2).

Front primary rods 108 and rear primary rods 103 form primary fixingpoints 103, 108 connecting top bracket 101 to lower bracket 102.

As represented schematically in FIG. 3A, primary vectors (v1, v′1)passing through primary fixing points 103, 108 between top bracket 101and lower bracket 102 of front attachment device 100 according to anembodiment of the invention, converge toward a primary convergence pointC1 located on axis A of turbojet engine 1.

Lower bracket 102 is, itself, directly connected to rear structure 4 offan cowl 2 of turbojet engine 1 by secondary attachments 109, 110, 111.Secondary attachments 109, 110, 111 include a secondary front rod 109,connecting front extremity 107 of lower bracket 102 to rear structure 4of fan cowl 2 of turbojet engine 1. More specifically, secondary frontrod 109 is mounted on central part 6 of rear structure 4 of fan cowl 2.Secondary attachments 109, 110, 111 include anti-torque controls 110located on rear extremity 105 of lower rod 102. Anti-torque controls 110connect two secondary rear rods 111 to a low part 8 of both branches 7of rear structure 4 of fan cowl 2. Using anti-torque controls 110enables an installation with a single degree of freedom for enginethrust, whereas cylindrical shapes of turbojet engine 1 require theinstallation of two lateral secondary rear rods 111. Thus, eachsecondary rear rod 111 is connected to a different, right or left, sideof turbojet engine 1. Secondary rear rods 111 connect rear extremity 105of lower bracket 102 to the front of turbojet engine 1. Anti-torquecontrols 110 require that the force transiting through each secondaryrear rods 111 is identical, and that the anti-torque controls110/secondary rear rods 111 assembly is insensitive to possibledistortions of turbojet engine 1.

As represented in FIG. 3B, secondary attachments 109, 110, 111 formsecondary fixing points connecting lower bracket 102 of front attachmentdevice 100 of the invention to turbojet engine 1. Secondary vectors (v2,v′2) passing through secondary fixing points 109, 110, 111 converge intoa secondary convergence point C2 located on axis A of turbojet engine 1.Secondary convergence point C2 is located upstream from primaryconvergence point C1, in relation to the moving direction of an aircraftprovided with turbojet engine 1.

As schematically represented in FIG. 3C, thrust load absorption vectorV, resulting from front attachment device 100 according to embodimentsof the invention, transits from secondary convergence point C2 toprimary convergence point C1, and is coincident with axis A of turbojetengine 1. Also, vector V, intended to absorb thrust loads P, inhibitsbending of turbojet engine 1. Thrust load absorption vector Vcompensates for thrust loads P of turbojet engine 1 along axis A ofturbojet engine 1, the torque on fan cowl 2 of turbojet engine 1 thenbecoming null.

1. A front attachment device for fastening a turbojet engine to anaircraft fixing strut, the attachment device being adapted to absorbturbojet engine thrust loads, wherein the attachment device comprises: atop bracket; a lower bracket; primary fixing points operably couplingthe top bracket to the lower bracket; and secondary fixing pointsadapted to connect the lower bracket to the turbojet engine, wherein anabsorbing thrust loads vector extends along a longitudinal axis of theturbojet engine resulting from a first convergence point of primaryvectors passing through the primary fixing points, and a secondconvergence point of secondary vectors passing through the secondaryfixing points, such that the absorbing thrust load vector is adapted totransmit the turbojet engine thrust loads to the aircraft fixing strut.2. The front attachment device assembly according to claim 1, whereinthe first convergence point of primary vectors is located on thelongitudinal axis of the turbojet engine.
 3. The front attachment deviceaccording to claim 1, wherein the second convergence point of secondaryvectors is located on the axis of the turbojet engine.
 4. The attachmentdevice according to claim 2, wherein the first convergence point ofprimary vectors is located downstream from the second convergence pointof secondary vectors.
 5. The attachment device according to claim 2, thedevice further comprising a primary attachment assembly, including atleast one front primary rod and at least one rear primary rod, such thatthe top bracket and the lower bracket are operably connected by twoprimary fixing points.
 6. The attachment device according to claim 3,the device further comprising a secondary attachments assembly includingat least one secondary front rod, and at least two secondary rear rods,such that the turbojet engine and the lower bracket are operably coupledby three secondary fixing points.
 7. The attachment device according toclaim 6, wherein the at least two secondary rear rods are mounted on thelower bracket through anti-torque controls.
 8. The attachment deviceaccording to claim 1, wherein the top bracket is operably couplable to afan cowl of the turbojet engine.
 9. An attachment device assemblycomprising a turbojet engine and the front attachment device accordingto claim 1.